The paper proposed Delta-tolling, a modified micro-tolling scheme, as an effective method to set dynamic toll values. Delta-tolling assigns tolls in a network proportionally to the difference between the link's current travel time and its free-flow travel time. This method, which is scalable for large and small transportation networks, incentivizes travel on less-congested routes.

METHODOLOGY

The analysis involved assessing link travel times and free flow travel times to set dynamic tolls based on a day-to-day pricing framework where delay was determined by link performance functions and a static equilibrium model; a within-day adaptive tolling framework using a cell transmission model (CTM) for dynamic network loading (with adaptive route choice but no equilibrium); and an adaptive tolling application using a new reservation-based intersection scheme for automated vehicles, evaluated using a microsimulation model.

FINDINGS

The modeling effort showed that Delta-tolling was able to achieve significant improvements in system performance with up to 32 percent improvement in average travel time. Benefits were seen both in small artificial grid networks with randomized parameters, as well as in larger networks representing real-world cities. Researchers noted that Delta-tolling does not necessarily require a computer-controlled vehicle, but could be enabled by current smartphone technology modified to interact with tolling systems.